Flash lamp



D 0, 1955 A. L. JESCHKE ETAL FLASH LAMP Filed June 11, 1952 IN VEN TORS A BN0; 0 c/ESCHKE BY 4N0 L W/5 CoNeor ATToRA/EK United States Patent FLASH LANIP Arnold L. Jeschke and Lewis E. Conroy, Warren, Pa, assignors to Solar Electric Corporation, Warren, Pa, a corporation of Pennsylvania Application June 11, 1952, Serial No. 292,840

4 Claims. (Cl. 67-31) The present invention deals with a flash lamp and more particularly with a flash lamp of the photo flash type.

Photo flash lamps generally comprise a sealed envelope containing a combustion supporting atmosphere, an ignitable substance and means for electrically igniting said substance to produce a brilliant flash of light es pecially suitable for'photographic purposes.

In the manufacture of photo flash lamps various structural considerations have been resorted to in order to provide explosion-proof envelopes, for example, envelopes of particular sizes and shapes, envelopes of laminated glass and plastic material, envelopes of lacquer coated plastic material, etc., whereby such envelopes are rendered suficiently resistant to fracture as a result of the heat generated by the combustible material and the pressure of expanding gases attendant therewith.

Since flash lamp envelopes are generally evacuated and filled with a combustion supporting atmosphere, special consideration, in conjunction with the aforesaid envelope structural consideration, has been directed to the sealing of lead-in wires through the envelopes and to means for evacuating and filling the envelopes with said atmosphere, whereby manufacture of the lamps is somewhat complicated and consequently expensive by the necessity of providing suitable hermetically sealed stems therefor associated with said lead-in wires and said evacuation and filling means.

However, in addition to the desirability of providing economical flash lamps, there is a need for the provision of some means to increase the speed of replacement of consumed flash lamps in order to decrease the time interval between pictures as, for example, in cases where the subject is available to be photographed during a very short period and where more than one photograph thereof is desirable. Under such conditions flash lamps as known still have to be manually inserted and manually removed before a replacement lamp can be inserted for subsequent use.

It is an object of the present invention to provide a flash lamp of inexpensive construction and which is resistant to fracture by the expanding gases contained therein upon ignition of combustible material within the lamp envelope. It is another object of the present invention to provide a flash lamp which eliminates the need for a hermetically sealed envelope containing a specific combustion supporting atmosphere. It is a further object of the present invention to provide a flash lamp having a simple stem structure which eliminates the critical requirements of stem structures such as in hermetically sealed lamp envelopes. It is a still further object of the present invention to provide a flash lamp which reduces the time of replacement of consumed lamps. Other objects and advantages of the present invention will become apparent from the description hereinafter following and the drawings forming a part hereof, in which:

Fig. 1 illustrates a partly elevational and partly sec- 2,727,377 I Patented Dec. 20-, 1955 ice tional view of a flash lamp according to the present invention, and

Fig. 2 illustrates a modification of Fig. 1.

The present invention relates to a flash lamp having an envelope constructed of light transmissive material in a shape and form suitable for use as a flash lamp envelope and provided with a means whereby the envelope is rendered substantially free of susceptibility to fracture by expanding gases within the envelope, whereby sealing stems as known in lamps of this type are substantially simplified, and whereby the lamp is capable of being replaced with increased speed.

With reference to Fig. 1, the flash lamp comprises an envelope 1 of light transmissive material preferably in the form of a bulb of plastic material having an internal coating 2 of lacquer or the like coating. However, the envelope may be constructed of any suitable light transmissive material either coated or uncoated, for example, materials such as glass, a lamination of plastic and glass, plastic having external and internal coatings of lacquer or the like, etc., since in the scope of the invention all such envelopes are applicable.

Sealed through the wall of the envelope 1 is a suitable means for the conduction of electrical energy, such as a pair of lead wires 3 and 4, which support internally of the envelope a filamentary wire 5 electrically connecting said lead wires and which is adapted, in view of its filamentary character, to ignite a combustible substance 6 in contact therewith, or otherwise in close proximity thereto, upon the application of suitable electrical energy therethrough.

The combustible substance comprises an ignitable or fulminating material which when energized burns at such a hi h rate that suflicient actinic energy is released to provide a flash. The substance to be ignited is usually made up of a mixture of finely divided zirconium together with an oxidizing agent such as potassium perchlorate and bonded together with a suitable binder such as nitro cellulose, or with finely divided magnesium or aluminum added to the ignition material, although where such ignition material is the sole source of light the additive material may be eliminated.

in combination with a flash lamp structure of the type as herein set forth, the envelope 1 is provided with an opening or aperture 7 through the envelope wall preferably iocated through the stem portion 8 of the envelope and leading through the said wall between the lead wires 3 and 4. However, the opening through the envelope wall may not be restricted to a particular location as the function thereof may be equally applicable to other portions of the envelope depending upon the particular form or configuration of the envelope.

It is apparent that the provision of opening through the envelope wall precludes the provision of a hermetically sealed envelope, and the interior of the envelope is under normal atmospheric pressure or such other pressure equal to the ambient or external pressure of the surrounding atmosphere.

Upon application of electrical energy to the lead wires 3 and 4-, or an equivalent thereof, the combustible material 6 is caused to ignite and burn as hereinbefore described in the presence of an internal combustion supporting atmosphere such as air or other equivalent ambient combustion supporting atmosphere, whereby a gaseous pressure is substantially instantaneously built up within the envelope attendant to the combustion within the envelope and is simultaneously released through the opening or aperture 7. As the gas generated within the envelope as the result of combustion is simultaneously released, it is apparent that the envelope is not subjected to an internal pressure as great as if the envelope were hermetically sealed and that, consequently, the envelope is less subject to fracture. envelope walls can be made thinner than other lamp envelopes in this art, or special reinforced envelope walls may be eliminated, whereby greater economy may be practiced.

Furthermore, since the flash lamp of the present invention is not concerned with hermetical sealing, precautions otherwise essential in providing sealed lead wires through the envelope wall or lamp stem, are eliminated, e. g. coated wires for protection against a substantially high oxygen content within hermetically sealed lamps for providing the combustion supporting atmosphere. Also, processes for evacuating and filling the lamp envelope with substantially high oxygencontaining gases are likewise eliminated, whereby further economy is practiced.

Apart from the aforesaid advantages, as the gaseous end products of combustion are rapidly expelled from the lamp through the opening or bore or aperture 7, the lamp itself is caused to be propelled in a direction opposite to that of the expelled gases, whereby the lamp is caused to be automatically disengaged from a suitable socket by the force of propulsion.

Although a single opening or aperture 7 through the envelope wall is illustrated, a plurality of such apertures are likewise applicable.

Therefore, it is apparent that the lamp herein described is a self-ejected lamp and so self-ejectable by means of the said aperture. The direction of the ejection of said lamp may be determined or guided by the position of a suitable socket associated with the base of the lamp in a suitable reflector, etc., and any modification of the lamp itself or of the socket cooperative therewith is considered Within the scope of the invention as long as such lamps are rendered self-ejectable by the propulsion forces of gases being expelled through an opening in the envelope as herein described.

Consequently, such lamps need only be manually inserted into a suitable socket and the manual removal thereof is eliminated, whereby thespeed of replacement of consumed lamps is at least doubled.

Fig. 2 illustrates a modification of the present invention in that the principal source of light is a second combustible material such as combustible wire 9 or the like, within the enveloped and ignited by means of a first combustible material such as a primer or fulminating substance such as herein described. The said foil 9 is preferably a magnesium foil, although other suitable ignitable metal may be employed, and in such instances it is desirable to incorporate suitable additives to the primer or fulminating material, e. g. finely divided magnesium or the like as hereinbefore set forth.

A modification such as illustrated by Fig. 2 is merely a matter of choice within the skill of the art and is applicable to the combination herein described since the lamp of the present invention is operable and fracture resistant as described with respect to Fig. 1.

While this description and drawing emphasizes the sim plified construction whereby the seal is accomplished by pressing the glass bulb around the lead wires, certain features and advantages are available even though more normal construction is used in which stem is incorporated by sealing its flare against the bulb wall.

Under such conditions the- V v 4 What we claim is: 1. An automatically ejectable flash lamp comprising a light transmissive envelope, electrical conductor means sealed through the wall of said envelope, an atmosphere of air under normal atmospheric pressure and a combustible material within said envelope, means cooperative with said conductor means for igniting said combustible material upon application of electrical energy to said conductor means, an ejector means comprising a straight open bore through the Wall of said envelope rendering said envelope an open envelope and whereby gaseous pressure generated as a result of combustion is released outwardly of said envelope through said bore thereby propelling said envelope.

2. An automatically ejectable flash lamp comprising a light transmissive envelope, a pair of electrical conductors sealed through the wall of said envelope, a metal filament electrically bridging said conductors within said envelope, an atmosphere of .air under normal atmospheric pressure and a combustible material within said envelope, said combustible material being ignitable upon application of electrical energy to said conductors, an ejector means comprising a straight open bore through the wall of said envelope rendering said envelope an open envelope and whereby gaseous pressure generated as a result of combustion is released outwardly of said envelope through said bore thereby propelling said en velope.

3. A flash lamp according to claim 2, whereinsaid envelope is composed of a thermoplastic material and at least one of the outer and inner surface of said envelope walls is coated with a light transmissive lacquer.

4. An automatically ejectable' flash lamp comprising a light transmissive envelope, a pair of substantially parallel electrical conductors sealed. through the wall of said envelope, said conductors leading inwardly and outwardly of said envelope, a metal filament electrically bridging said conductors within said envelope, an atmosphere of air under normal atmospheric pressure and a combustible material within said envelope, said combustible material being ignitable upon application of electrical energy to said conductors, an ejector means comprising a straight open bore through the Wall of said envelope between said parallel conductors rendering said envelope an open envelope and whereby gaseous pressure generated as a result of combustion is released outwardly of said envelope through said bore thereby propelling said envelope.

References Cited in the file of this patent UNITED STATES PATENTS 2,013,371 Van Liempt Sept. 3, 1935 2,034,029 Froelich Mar. 17, 1936 2,046,388 Kurlander July 7, 1936 2,091,601 Leijdens Aug. 31, 1937 2,254,888 De Margitta Sept. 2, 1941 2,333,725 Kreidler Nov. 9, 1943 2,361,495 Pipkin Oct. 31, 1944 FOREIGN PATENTS 403,427 Great Britain Dec. 19, 1933 

